This invention relates to a novel composite flexible material, and more particularly, it relates to a composite material comprising a flexible sheath covering a roving of continuous fibers of any type, be they mineral, organic or metallic, impregnated to the core with thermoplastic powders, the melting point of which powders being greater than or equal to that of the flexible sheath, and to processes and apparatus for preparing such composites.
A composite material has already been described in French parent patent application No. 83 10632. In this application, the melting point of the material used for the powder with which the fibers were impregnated was, however, restricted to a level considerably higher than that of the sheathing material's melting point.
The new composite material in accordance with the present invention is importantly superior in its flexibility. The prior art composites, as shown in French patent application No. 81 21545, for example, although pliable, are rigid materials. They are in the form of strips, five to ten mm in width and about one mm thick, and contain continuous parallel fibers like a reinforcement solidly embedded in a thermoplastic matrix which has been subjected to fusion and subsequent solidification by cooling.
Clearly, this type of material can only be rigid; experience also shows that it breaks when bent.
An object of the present invention is to overcome this drawback which proves a great handicap, in those applications in which the composite is to be placed around metal objects with a small bending radius (a radius of 8-10 mm, for example), such as those encountered in production of automotive components (steering wheel frames, hydraulic cylinders, etc.).